Multiple temperature refrigerator



April 25, 195() R. L. BENSON IIULTIPLE TEMPERATURE REFRIGERATOR Filo@Sept. 7, 1945 Patented Apr. 25, 1950 MULTIPLE TEMPERATURE REFRIGERATORRalph L. Benson, Birmingham, Mich., assignor to Aveo ManufacturingCorporation, a corporation of Delaware Application September 7, 1945,Serial No. 614,919

s claims (ci. ca -11s) The invention relates to refrigerating systems.v

One obiect of the invention is to provide a refrigerating system whichincludes an evaporator in a cooling compartment and an evaporator in afreezing compartment and in which one of the evaporators consists ofcontinuous tubing of substantially uniform and relatively small diameterfor progressively producingr the desired pressure drop to provide thediilerential temperatures required for maintaining cooling temperaturein one compartment and freezing temperature in the other compartment.

Another object of the invention is to provide a refrigerating systemwhich includes an evaporator coil in the cooling compartment associatedwith freezing trays and formed of a length of relatively small anduniform diameter tubing for producing progressive drops in pressure ofthe refrigerant and causing ice to be produced successively in the traysso that the water in one of the trays will befrozen faster than in theother trays.

Another object of the invention is to provide a refrigerating vsystemwhich includes cooling and freezing compartments and evaporator coilswhich are simple in construction and can be economically fabricated.

Other objects of the invention will appear from the detaileddescription.

The invention consists in the several features hereinafter set forth andmore particularly deilned by claims at the conclusion hereof.

In the drawings:

Fig. 1 is a view of a refrigerating system embodying the invention.

Fig. 2 is a perspective of the evaporator coil in the coolingcompartment.

The invention is exemplified with a refrigerator cabinet I, whichincludes a cooling compartment 2, and a separate freezing compartment 3.The cabinet is provided with walls for insulating the cabinet andinsulating the compartments from each other. The cabinet is usuallyprovided with a. door or doors `for access to the compartments.

The refrigerating apparatus comprises a unit 4 which includes anenclosed electric motor and a compressor for the refrigerant driven bysaid motor, which may be of any suitable construction, as wellunderstood in the art, for compressing and liquifying refrigerant. 'I'hepressure or discharge side of the compressor is connected by a pipe 5 toa condenser 6.

An evaporator, generally designated 20, is 1ocated within the coolingcompartment 2. Evaporator 20 comprises a box-like member 2| and 2 f anevaporator coil 22. Coil 22 is connected by a capillary tube 9 to thedischarge side of the condenser for delivering restricted andcontrolledow of refrigerant from the high pressure side of condenser 6to coil 22. Member 2| comprises parallel side-walls 24. a back-wallusually located forwardly of the back of compartment 2. a top-wall 25, abottom-wall 26, shelves 21 and 28 substantially parallel withbottom-wall 26, andl a door 23 for closing the front of member 2| andproviding access to the spaces in said member. Trays 29, 30 and 3| forfreezing cubes are supported on bottom-wall 26 which serves as a shelf,and shelves 21 and 28, respectively.

The evaporator coil 22 consists of continuous tubing of relatively smallbore and comprises a looped member or section 34 secured in heatexchange relationship to the underside of bottomwall 26 which functionsas a shelf for one of the freezing trays, a looped member or sectionsecured in heat exchange relationship with the underside of shelf 21, aleg 31 connecting members 34 and 35, a looped member or section 36secured in heat exchange relationship with the underside of shelf 28,and a connecting leg 38 between members 35 and 36. Coil 22 is connectedby means of a tube I3 of equal or greater size bore than the bore ofcoil 22 to an evaporator I0 for the freezing compartment 3. Therefrigerant from capillary tube 9 circulates rst through the lowermember 34, then through the intermediate member 35, and then through theupper member 36 so that the progressively greater drop in pressure inmember 36 will cause ice to be frozen first in the upper tray 3|, thenin the intermediate tray 39, and then in the lowermost tray 29. Sections34, 35, 36 of coil 22 all operate at temperatures suiliciently low tofreeze the water in trays 29, 30, 3|. This low temperature imparted tothe bottom-wall 26 and shelves 21 and 28 conducts heat, which coupledwith the heat removed from side-.walls 24 of member 2| by convectioncurrents over shelves 21 and 28 in member 2| will maintain theside-walls 24 of member 2| at a sufficiently low temperature to maintainthe temperature in the cooling compartment 2 Within the desiredtemperature range.

An evaporator I0 is provided for the freezing compartment 3 formaintaining freezing temperature in said compartment. A tube I3 conductsrefrigerant from the discharge side of the evaporator section 36 of coil22 to the evaporator I0. The discharge side of the evaporator I0 is'connected to an accumulator I4 which is connected bya suction-tube I5connected to the suction-side of the compressor in the unit 4,V andincludes a portion I6' in heat-exchange relation with capillary tube 9.'

The evaporator I for the freezing compartment 3 comprises a sheet metalwall or liner 40 extending around the bottom, top, sides and back offreezing compartment 3 and a coil 4I of looped tubing which is securedin heat exchange relationship to the outer faces of liner 40. The boreof coil 22 is so proportioned relatively to evaporators 20 and I 0 andthe capacity of the compressor in unit 4 that it will cause asubstantial pressure drop due to the flow of the refrigeranttherethrough. The heat laden refrigerant flows from evaporator IIIthrough an accumulator I4 and tube I5 to the suction side of thecompressor in unit 4. The tubing of evaporator coil 4I is of suitablediameter so that there is substantially no drop of pressure in therefrigerant flowing from tubel I3 to suction tube I5, thereby producinga freezing temperature, for example, 6 to 8 Fahr. in the freezingcompartment 3 at the highest possible refrigerant pressure.

It has been found that with a standard onei'lfth horse-power compressorunit 4 and a standard capillary tube 9, the tubing of coil 22 having abore of .125 inch and a length of 19.5 feet using Freon 12 asrefrigerant, resulted in a difference in the pressure across theevaporator 20 of about fifteen pounds per square inch or about 30 Fahr.It has also been found that when the bore of the tubing of coil 4I ofevaporator I0 is approximately one-fourth inch in diameter andapproximately 24 feet in length, there is little, if any, difference inpressure between that at the outlet of tube I3 and that at theaccumulator I4. It has also been found that in lieu of the refrigeratedliner type of evaporator I0, a refrigerated or cooling plate of the typegenerally known as a D0le" plate may be used.

The operation of the motor of the compressor may be automaticallycontrolled for maintaining predetermined temperature ranges in thecompartments, respectively, by a thermostatic switch I6 responsive tothe temperatures in the cooling compartment 2 and the evaporator 20.Current is supplied for the operation of the motor by line-conductors I1and I8 which are connected to a suitable source of electric current,switch I6 being included in one of the line-conductors to automaticallystart and stop the motor and cornpressor responsively to a desired orpredetermined range of temperature in the cooling compartment.

The operation will be as follows: When the temperature in the coolingcompartment 2 or the temperature in the ice trays 29, 30, 3|, drops to apredetermined temperature thermostatic switch I6 will close the circuitfor the motor of unit 4 and the compressor will compress refrigerant andcirculate it from the high pressure side of the compressor, successivelythrough the condenser 6, capillary tube 9, sections 34, 35 and 36 ofevaporator coil 22, tube I3, evaporator coil 4I and suction-tube I5 tothe low pressure side of the compressor. Capillary tube 9 restricts theflow of the refrigerant to the evaporator coil 22, thereby reducing theliquid pressure from that in the condenser 6 to the pressure desired atthe inlet to the evaporator coil 22. There lwill be progressive drop inpressure ofthe refrigerant in sections 34, 35, 38 of evaporator coil 22,which will cause the upper section 36 to freeze the cubes in theuppermost tray 3 I, then in the intermediate tray 30, and then in thelowermost tray v29, and the refrigerant leaving coil section 88 will beat the pressure in the evaporator I0.

In practice, it has been found to be advantageous, when ice cubes arequickly desired,vto freeze the cubesin one tray as quickly as possible.The refrigerant flowing through section 36 will freeze the cubes in theupper tray 3l more quickly than those in the intermediate and lowertrays, so that the freezing of some cubes will be expedited to renderthem more quickly available. The progressive pressure drop in sections34, 35, 36 of evaporator coil 22 tends to reduce or avoid theaccumulation of frost which dehumidifles compartment 2 because the coilsection 34 which is exposed to the air in compartment 2 is only slightlybelow freezing temperature. The temperature of the fast-freezing `shelf28 is subs'fantially below that of the exposed bottom-wall 26 and isisolated from the air in compartment 2 by said wall 26 and shelves 21,28, the rear-wall of evaporator member 2I and the door 23. 'I'herelatively small size of the tubing forming the evaporator coil 22 andthe progressive pressure drop therein prevent trapping of liquid in theupper section 36 during 01T cycles. The pressure drop of the refrigerantcirculating through coil 22 will reduce the refrigerant pressure flowinginto tube I3 and evaporator ID to produce the desired temperature range,for example, 6 to 8 Fahr., in the freezing compartment 3 for thepreservation of the products therein in a frozen condiion. When thetemperature in the cooling compartment reaches the temperature desired,thermostatic switch I5 will open and cause the motor and compressor tobe stopped and the circulation of the refrigerant to be discontinued.

The invention exemplifies a refrigerating system withan evaporator coilformed of sections for producing a progressive pressure drop of therefrigerant circulating therethrough to expedite the freezing of thecubes in one of the freezing trays in advance of the others. Theinvention also provides a refrigerating system which comprises a coolingcompartment and a freezing compartment and evaporators therein formed ofcontinuous tubing for producing the desired differential temperatures inthe cooling compartment and the' freezing compartment without valves ormoving parts.

The invention is not tobe understood as limited to the detailsdescribed, since these may be modified within the scope of the appendedclaims without departing fr'om the spirit and scope of the invention.

Having thus described the invention, what I claim as new and desire tosecure by Letters Patent is:

l. Refrigerating apparatus comprising a cooling compartment, anevaporator disposed in said compartment, said evaporator including aseries of tube coils providing a plurality of spaced sections connectedin series, freezing trays associated with said sections, refrigerantliquefying means connected to the inlet of said evaporator, and a returnline connecting said refrigerant liquefying means to the outlet of saidevaporator, the ratio of the internal diameter of said tube to thelength thereof being of the order of .125 to 234 for progressivelyproducing freezing in said trays associated with said sections.

2. Refrigerating apparatus comprising a cooling compartment, anevaporator in said compartment, said evaporator including a series oftube coils providing vertically-spaced horizontally-disposed sectionsconnected in series, freezing trays asoasvo of said evaporator, theratio of the internal di` ameter of said evaporator tube to the length`thereoi.' being of the order o'f .125 to 234 for progressivelyproducing freezing'in said trays.

3. In a refrigerator having a plurality of compartments to be cooled todifferent temperatures, a refrigeration system comprising an evaporatordisposed within the highr temperature compartment, said evaporatorcomprising Va. plurality of looped sections connected in series andadapted to receive ice trays, a compressor, a condenser, a deliveryconduit provided with a highly restricted passageway throughout itslength connecting said condenser and the inletof said evaporator, saidevaporator tubing having a restricted passageway therethrough of uniformdiameter throughout its length of greater diameter than that of saiddelivery conduit and providing a progressive pressure drop and differentrate of freezing in the trays in each of said sections, a secondevaporator connected to the outlet of said first-mentioned evaporatorcomprising a continuous tubing extending substantially entirely aroundfour walls of the lower temperature compartment, said second evaporatorhaving a passageway therethrough having an internal diameter at leasttwice that of the internal diameter of said firstmentioned evaporatortubing and providing a minimumV pressure drop throughout saidsecondmentioned evaporator, and tubing connecting the outlet of saidevaporator to the inlet of saidcomi presser. A

4. In a refrigerator having a plurality of comprovidingvertically-spaced horizontally disposed sections connected inseriesfreezing trays associated with said sections, a compressor, acondenser, a delivery conduit provided with a highly restrictedpassageway through its length connecting said condenser and the inlet oisaid evaporator, said evaporator tubing having a restricted passagewayof uniform diameter throughout its length and of a greater diameter thanthat of said delivery conduit, said evaporator tubing also having theratio of itslength to its diameter such that a progressive pressure dropis produced through said evaporator sections and a diierent rate offreezing is produced in the trays associated with each of said sections,and tubing connecting the outlet of said evaporator to the inlet of saidcompressor.

6. In a refrigerator having a compartment to be cooled, a refrigeratorsystem comprising. an evaporator disposed within the compartment, said.evaporator comprising a series of tube coils proin saidtrays associatedwith each of said sections,

partments to be cooled to different temperatures, a refrigerator systemcomprising an evaporator disposed within thel -higher temperaturecompartment, said evaporator comprising continuous tubing including aplurality of looped sections connected in series and adapted to receiveice trays, a compressor, a condenser, a delivery conduit` having ahighlyy restricted passageway throughout its length connecting saidcondenser and said evaporator, the ratio of the internal diameter ofeach said evaporator tubing to the `vlength thereof being of the orderof .125 to 234 for providing a different-freezing rate in the trays ineach of said evaporator sections, an evaporator Aconnected to the outletof said rstmentioned evaporator, .said second-mentioned -evaporatorVcomprising a continuous conduit extending substantially. entirelyaround four walls of said lower temperature compartment, the ratio ofthe internal diameter of said conduit to itslength being oi the orderof- .25 to 288 for providing a minimum pressure drop throughout saidevaporator, and tubing connecting the outlet of ,said second evaporatorto the inlet of said compressor.

5. In a refrigerator having a compartment to be cooled, a refrigeratorsystem comprising an evaporator disposed within said compartment. nidevaporator comprisingl a series of tube coils viding vertically-spacedhorizontally disposed sections connected in series, a freezingtrayassoci-` ated with each of said sections, a compressor, a

' condenser, a delivery conduit provided with a highly restrictedpassageway through .its length connecting said condenser and the inletof said evaporator, said evaporator tubing having a'restrictedpassageway of uniform diameter throughout its length and of a greaterdiameter than that of said delivery conduit, the tubing of said 'evaprator creating a sufiicient' restriction to the flow of refrigerant toproduce a substantial and progresslve drop in the pressure of therefrigerant between the inlet and the outlet of said evaporator wherebya different rate of freezing is producedA and tubing connecting ratortothe inlet of said compressor.

RALPH L. BENSON. REFERENCES f The following references are of record. in

ille of this patent: UNITED sTA'rEsPATEN'rs OTHER REFERENcEs Articlenamed rressure Drops 1n Lines," by Guy R. King onypages 41-44 of theFebruary issue 1949, of Refrigeration,publlshed. `l Company,- 433Principles of.Refrigeration,*\ by W, published by Nickerson Collins Co..mens l by Nickerson and Collins Ave., Chicago, Ill. Y

annee. Third edition.

the outlet of saidevapo-

